Auxiliary method based on effective medium theory for biosensing applications using surface plasmon resonance

Abstract

In this thesis, an auxiliary method based on the effective medium theory is applied to surface plasmon resonance (SPR) biosensing in order to extract quantitative properties of the biosensor functionalization. An automatized SPR biosensor array was built to perform intensity measurements in an automatized and controlled manner. Five gold layers with different Bovine Serum Albumin (BSA) deposition times were measured in the sensor and the refractive index and thickness of the sample were both estimated using the gradient descent method in combination of a theoretical model. These parameters were then introduced into two distinct effective medium theories in order to change a qualitative description of the surface coverage into a quantitative one. Yielding values of 30 % for the linear effective field approximation (EFA) and 50 % for the non-linear Quasicrystalline Approximation (QCA). Finally, a qualitative detection of a BSA-Carbamazapine (CBZ) was done utilizing the sensor in which there is a significant difference in the response of the sensor compared to the one of bare gold and BSA.